Correlation Between E6 and E7 Oncogene Mutation Human Papilloma Virus High Risk Type 16 with Retinoblastoma Protein Expression in Cervical Cancer

Abstract

Introduction: The E6 and E7 oncoproteins of high-risk Human Papillomavirus (HPV) have crucial roles in cervical cancer pathogenesis by inhibiting p53 and retinoblastoma protein (pRb) which are tumor suppressor genes. Genetic sequence mutations of E6 and E7 oncogenes can affect E6/E7 protein functions that will change E7-pRB interaction. Furthermore, this condition will influence progression cervical cancer progression in several intratypic variants of high-risk HPV type 16. Methods: A cross-sectional study was conducted from September 2020-September 2021, at the Obstetrics and Gynecology Outpatient Clinic, Prof Dr I. G. N. G. Ngoerah General Hospital. Consecutive sampling was taken by collecting cervical cancer tissue followed by isolation, amplification, and gene sequencing to assess E6 and E7 mutations. The expression of pRb was measured by immunohistochemical staining (IHC). Results: From 100 cervical cancer subjects, 31 subjects were found HPV16 positive (19 wildtype and 12 mutants). The proportion of E6 and E7 mutants was 25.8% and 12.9% respectively. This study shows that T27C/F9F; A360G/E120E and G371A/R124K variants were found on E6 oncogene mutations, meanwhile, A86C/N29T; A86G/N29S; C229T/R77C and T285C/S95S variants were detected on E7 oncogene mutations. The types of E6 mutations were T27C (16.1%), A360G (6.4%) and G371A (1 subject; 3.2%). In addition, pRb expression was stronger in mutant group than wild-type group 60.5% vs. 53%. There was no correlation between retinoblastoma protein expression and mutations E6/E7 oncogene HPV Type 16 (PR 0.22; 95% CI 0.03-1.6; p value 0.10). Conclusions: In cervical cancer, there is no significant difference between the expression of retinoblastoma protein in mutant vs wildtype E6 and E7 oncogene HPV16.